Modern window coverings can be raised and lowered for selectively blocking or filtering light in a room. A common method of achieving this result is through the use of one or more control cords. Some control cords have open ends, while others form a closed loop or end.
Both the closed end and open end control cords could be unsafe.
It is also possible for the cords on the opposite side of the control cord to become loose and create a loop large enough to fit the head of a child or pet as is shown in FIG. 3.
One example of a prior art tension device is disclosed in U.S. Pat. No. 6,463,987 to Nevins. But there is a major drawback to the Nevins invention and other current tension devices. These tension devices need to be installed by the operator separately from the window covering itself. Often the operator, for whatever reason, installs the window covering without installing the tension device. When this happens, the advantages of the tension device are lost.